Thermionic current transformer



Oct. 11, 1927. 5, 7

L. H. JUNKEN THERMIONIC CURRENT TRANSFORMER Filed Dec. 1925 Inventor: Lawrence H. Junken,

by i/M M T His Attov ney.

Patented Oct. 1 1,.1927.

UNITED STATES 1,645,057 PATENT OFFICE.

uwmcn H. mum, Oil SCHINIG'ILDY, NEW YORK, ABBIGNOB T GENERAL ELEG- TRIO CIIJKPANY A CORPORATION 01' NEW YORK.

OHIO CURRENT 'I'RANSI'ORHEB.

a lication Med December a0, 1025. Serial No. 78,229.

My invention relates to apparatus for obtainmg a transformation of current either direct or alternating of any frequency and voltage. My invention is applicable for use a as an instrument currenttransformer and has certain advantages over the ordinary t e of instrument current transformer.

n carrying my invention into elfect 1' make use of an electron discharge device and In preferably of such a device known in the art as a magnetron. The output current of a. magnetron tube is verv sensitive to changes in the magnetic field threading the tube and I make use of this characteristic to provide a thermionic current transformer by placing the tubewithin the influence of the natural magnetic field which is set 11 around a conductor due to a. current owing therein. The apparatus is so adjusted that the plate current varies with the current in the adjacent conductor and the change in the plate :urrent due to the current flowing in the adjacent conductor may be calibrated and measured or used to operate relays and other devices in the usual way.

For a better understanding of my invention reference is made in the following description to the accompanying drawing. Fig. 1 of which shows the arrangement of the apparatus when used as an alternating current transformer; Fig. 2 is a curve illustrating the characteristics of the apparatus of Fig. 1; and Fig. 3 illustrates the characteristics of the apparatus as adjusted for a diflerent operating condition.

Referring to Fig. 1, 10 represents an electric conductor insulated or otherwise and for the purpose of explaining my invention it will be assumed to be a high voltage alternating current power cable. When current flows in such a cable a concentric magnetic field, sometimes called the magnetic whirl, is set up around the cable as re resented by the lines 11. This magnetic fie d is proportional to the current and if the current is alternating the field reverses with the current. 12 represents a magnetron tube having its axis placed at. right. angles to the conductor 10 at one side thereof and within the influence of the field 11 thereof. The magnetron tube consists of a sealed glass container which is highly evacuated and contains an axial filament or cathode 13 and a cylindrical anode 14 concentrically arranged with respect to the filament 13 and .he walls of the tube. About the tube is a. solenoid 15 for the purpose of producing a has1c magnetic field in the tube arallel to its axis. The filament is heated m a battery 16 and between the filament and anode 13 connected the external circuit containing the battery 17., the prima ry of a transformer 18. and an adjustable resistance 19. A battery 20 connected in circuit with an adjustable resistance 21 is provided to supply the coil 15 with an adjustable current. The secondary circuit of the transformer contains a translating device 22, such as an ammeter or relay.

Asmore fully explained in the Physical Review No. 3. September, 1923, pages 279 to 292. the characteristics of the magnetron tube are such that the strength of the magnetic field threading the tube parallel to the axis controls the number of electrons which flow fromthe filament to the anode under certain conditions. Thus with no field in the tube the electrons are free to flow to the anode unimpeded in an amount depending upon the voltage thereacross and to some extent upon the temperature of the filament. These factors are maintained constant and consequently do not afi'ect the result. As the field strength is increased a point is reached where some of the. electrons given out by the filament do not reach the anode and the current in the external circuit starts to decrease. These results are plotted in Fig. 2 where the ordinates represent current in the external circuit and the abscissa represents the field strength. Thus with zero field the plate current is OT and does not start to decrease until the field has reached a value OF. l pon a further increase in field the current decreases proportionately and reaches suhstnntiallv zero at a field strength represented by OF". Thus between the values of field strength represented by F and F the tube is very sensitive to changes in field strength. the output current being inversely proportional thereto. I make use of this range of the device in practicing my invention.

The strength of the field produced by coil 15 is adjusted to near the central of this range such as to the value represented by F. which allows a direct current l to flow in the external circuit represented. Now the device is placed adjacent. to conductor 10 as represented in Fig. 1 so that the natural flux lie field of conductor will alternately increase and d basic field stren through the tube. The field produced h conductor 10 may be represented as at considering the dotted line 24 as a zero flux line. This alternating field is superimposed on the field produced by coil and conseu'ilsntly alternately increases and decreases current in the external circuit, giv ng the elect of superimposing an alternatmg current such as is re resented at on the direct current I. T e alternating current component thus flowing in the external circuit may be arated out b the trans former 18 so the current owing in the device 22 is pro rtional to that flowing in conductor 10. will be noted that the ratio to the int re resented the field stren h F" the basic zurrent tlowing in the.ex terual circuit is reduced substantially to zero so that the current produced by an additional alternatin flux, such as the flux 23, will reduce only he sitive half waves of an a ternatin curren as represented at 27, or, if the ad ltional flux be produced by a current flowing in conductor 10 It will be of constant direction, and it up to that produced by coil 15 a resulting trcct current will flow m the external circuit of tube 12 which will be proportional to that of conductor 10 and me be measured directly by an ammeter in t a anode circuit of tube 12 as represented at 28 when the switch 29 is thrown to the left. This will generally be the preferable arrangement when measuring very high frequency alternating current or direct current. The apparatus ma be used as a potential transformer by ma mg the curren in conductor 10 proportional to the voltage to be measured.

It will thus be seen that I have provided transformer apparatus which is applicable for either direct or alternatinf current cirunits of any frequency and v0 hi8, without cu or otherwise disturbin he circuit. The evice takes no energy cm the pm- 111 circuit other than that which is ordinatil lost in producing the ma etlc whirl 11. t ieeasily ad'usted for di erent transformer ratios an problems. i

In accordance with the provisions of the patent statutes I have described the principle of operation of my invention together involves no insulating with the apparatus which I now consider gth to re resent the best embodiment thereof;

but desire to have it understood that the apparatus shown and described is on] illustrative and that the invention may carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. Thermionic current transforming apparatus comprising a primary war notor, an electron discharge device having an output circuit the current of which is re s Jonsive to changes in flux variations trough said device means for producing a constant flux field through said device, said device being positioned adjacent and to one side of said primary conductor so that at least a portion of the natural flux surround ing said conductor due to current flowing therein is superimposed upon the constant field through said device, and current rensivc means associated with the output circuit of said device.

2. Thermionic current transforminga ratus comprising a grim power can notor, an electron disc urge evice having an output circuit, the current of which is responsive to flux variations through said device, means for producin a constant magnetic field through said evice, said device being msitioned adjacent and to one side of said prima conductor so that at least a portion of 1118 natural flux surrounding said conductor due to current flowing therein is superimposed upon the constant magnetic field of said device in a manner to vary said field in response to variations in the current flowing in said primary conductor, and current res nsivc means associated with the output circuit of said device responsive only to the current in said circuit which is due to the su rimposed portion of the flux through said device.

3. A high voltage power cable and means for obtaining a current naive to the current flowing in said on Io comprising a ma ctron tube positioned with its axis at rig it angles to the axis of said cable and on one side thereof within the influence of the magnetic whirl of said cable, an output circuit for said tube, means for producing a constant flux along the axis of said tube of such a strength as to limit the output current of said tube. and current res nsive means associated with the output circuit of said tube.

4. Thermionic current transforming a paratus comprising a primary power con uctor. a magnetron tube havin an output eircnit. said tube adjacent sai conductor and to one side thereof so that current flowing in said conductor will produce a proportionate flux through said tube. and means for producing a constant flux through said tube of such strength as to just reduce the outiii put current of said tube to substantially zero when no cu rent is flowing in said primary conductor.

5. Thermionie current transforming apparatus comprising a primary power conductor, a magnetron tube having an output circuit. said tube being positioned adjacent said conductor and to one side thereof so that current flowing in said conductor will produce a proportionate flux through said tube,

and means for producing a constant flux through said tube of such strength as 'ust to reduce the output current of said tube eproximately to zero when no current is flowmg in said primary conductor, the direction of said proportionate flux, when produced by a direct current in the primary conductor, being such as to oppose said constant flux. In witness whereof, I have hereunto set my hand this 24th day of December, 1925.

LAWRENCE H. JUNKEN.

through said tube of such strength as 'ust to reduce the output current of said to e aproximately to zero when no current is flowmg in said primary conductor, the direction of said proportionate flux, when produced by a direct current in the primary conductor, being such as to oppose said constant flux. In witness whereof, I have hereunto set my hand this 24th day of December, 1925.

LAWRENCE H. JUN KEN.

Certificate of Correction.

Patent No. 1,645,057.

Granted October 11, 1927, to

LAWRENCE H. J UNKEN.

It is hereby certified that error appears in correction as follows:

numbered patent requiring the printed specification of the above Page 2, line 1253. claim 4, before the word adjacent insert the Word being; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent ()fiice.

Signed and sealed this 22d day of November, A. D. 1927.

M. J. MOORE, Acting C'onvmiasiorwr of Patents.

Certificate of Correction.

Patent, No. 1,645.057. Granted October 11, 1927, to

LAWRENCE H. JUNKEN.

It is hereby certified that error appears in the printed sperih'cation of the ahovenumbered patent requirin; correction as follows: Page 2, line 125. claim 4, before the word adjacent insert the word being; and that the said Letters Patent should he read with this rorrection therein that the :szune may conform to the revord 0f the case in the Patent ()fiice.

Signed and sealed this 22d day of November, A. D. 1927.

[SEAL] M. J. MOORE,

Acting Commissioner of Pfltents. 

